1. Field
This invention relates to the field of optical waveguide repair, and more specifically, to a multi-layered apparatus and system for addressing structural differentials introduced when optical cables are spliced.
2. Background
Optical fiber cables, known for their high speed and bandwidth, are brittle glass or polymer fibers surrounded by a protective layer. Fiber optic cables can include large numbers of signal-carrying fibers, each fiber having a diameter of less than a human hair. The fiber-optic “bundle” is protected by an outer cable casing.
Fiber optic cables are often buried or submersed, and effectively under high pressure below ground or under water. They may need to be removed and redeployed which can include being rewound on reels. They may also be subjected to pulling forces (“tension”) when the cable is being deployed.
The thin filament fibers within a cable may break when the outer housing of a cable is pierced, bent sharply (“kinked”) or crushed. When a breakage in the fibers occurs, each fiber must be spliced back together. Two fiber segments are positioned end-to-end and heat fused to form a single optical fiber.
It is well known in the art that once the cable is repaired, the repaired cable is at a high risk of subsequent breakage due to several specific factors known in the art that contribute to this risk.
First, there is increased vulnerability because the original protective layers of the cable must be stripped during the repair process. It is a problem known the art that after a repair, when the structural layers are not restored, the cable is substantially weakened and does not have the same resistance to tension, bending or the original conditions which caused the cable to break prior to the repair.
Second, the splicing operation and/or makeshift strengthening and protecting measures result in geometric abnormalities and protuberances on the outer surface of cable which may cause the repaired cable to catch or snag objects moving across its surface. This may cause damage to the cable when moving or respooling.
Third, many repair processes result in rigid cable segments which are vulnerable to breakage because they cannot curve gently. This subjects the cable to kinking at a sharp angle at each end of the rigid segment.
Many attempts have been made in the prior art to reinforce fiber optic cable after a repair operation has been completed. For example, U.S. Pat. No. 5,884,003 A to Randy G. Cloud et al. (Cloud '003) teaches the use of a rigid case for enclosing and storing optical cable splices. While the Cloud '003 device may protect the splice, it creates problems associated with the storage and transportation of fiber optic cable. Use of this prior art device, and others like it, results in large, rigid segments of cable that cannot be easily wound on a spooling device for storage. Furthermore, the cable is vulnerable to kinking at each end of the rigid case.
Current repair methods and kits do not restore the structure of the original layers, focusing instead on providing a portable sleeve that can be used to rapidly cover the splice. The shrink-wrapped covering provides a simple mechanical interface but does not provide multiple layers of protection. Commercially available kits often comprise a single type of fusion splice sleeve for use after a fusion splicing operation. These kits may be a good on-site solution, but alone it has been shown in the art that they are inadequate to assure continued, reliable communications after a repair.
It is desirable to have a multi-layered splice protection apparatus or system which retains near to the original diameter of the cable, avoids creating a rigid segment, approaches the stiffness of the original cable, and continues to hold the same tension as the original cable in service.